通过Al掺杂调节TiN金属栅功函数

The effect of Al incorporation on the effective work function(EWF) of TiN metal gate was systematically investigated.Metal-oxide-semiconductor(MOS) capacitors with W/TiN/Al/TiN gate stacks were used to fulfill this purpose.Different thickness ratios of Al to TiN and different post metal annealing(PMA) conditions were employed.Significant shift of work function towards to Si conduction band was observed,which was suitable for NMOS and the magnitude of shift depends on the processing conditions.     

TiN/TaN 厚度变化对nMOSCAP栅叠层有效功函数的影响

We evaluated the TiN/TaN/TiA1 triple-layer to modulate the effective work function （EWF） of a metal gate stack for the n-type metal-oxide-semiconductor （NMOS） devices application by varying the TiN/TaN thickness. In this paper, the effective work function of EWF ranges from 4.22 to 4.56 eV with different thicknesses of TiN and TaN. The thinner TiN and/or thinner in situ TaN capping, the closer to conduction band of silicon the EWF is, which is appropriate for 2-D planar NMOS. Mid-gap work function behavior is observed with thicker TiN, thicker in situ TaN capping, indicating a strong potential candidate of metal gate material for replacement gate processed three-dimensional devices such as FIN shaped field effect transistors. The physical understandings of the sensitivity of EWF to TiN and TaN thickness are proposed. The thicker TiN prevents the A1 diffusion then induces the EWF to shift to mid-gap. However, the TaN plays a different role in effective work function tuning from TiN, due to the Ta-O dipoles formed at the interface between the metal gate and the high-k layer.     

PMOS剂量计的退火特性

研究了PMOS剂量计在不同温度和栅偏置下的辐照退火表现.结果表明：温度和退火偏置条件是影响初始退火速率和退火幅度的重要因素,较高退火温度下,退火速率高,幅度大;相同退火温度下,正偏置与负偏置相比有加速退火的作用,其退火幅度也较大.在180℃,零偏条件下获得了最快的100％的退火效果;用模型讨论了实验结果.     

锗预非晶化注入对镍硅(NiSi)金属栅功函数的影响研究

随着超大规模集成电路技术的发展,CMOS器件的制备过程需要同时引入金属栅和超浅结等新的先进工艺技术,因此各种新工艺的兼容性研究具有重要意义.本文研究了超浅结工艺中使用的锗预非晶化对镍硅(NiSi)金属栅功函数的影响.对具有不同剂量Ge注入的NiSi金属栅MOS电容样品的研究表明,锗预非晶化采用的Ge注入对NiSi金属栅的功函数影响很小(小于0.03eV),而且Ge注入也不会导致氧化层中固定电荷以及氧化层和硅衬底之间界面态的增加.这些结果表明,在自对准的先进CMOS工艺中,NiSi金属栅工艺和锗预非晶化超浅结工艺可以互相兼容.     

PMOS剂量计的退火特性

研究了 PMOS剂量计在不同温度和栅偏置下的辐照退火表现 .结果表明 :温度和退火偏置条件是影响初始退火速率和退火幅度的重要因素 ,较高退火温度下 ,退火速率高 ,幅度大 ;相同退火温度下 ,正偏置与负偏置相比有加速退火的作用 ,其退火幅度也较大 .在 1 80℃ ,零偏条件下获得了最快的 1 0 0 %的退火效果 ;用模型讨论了实验结果     

偏置对PMOS剂量计辐照响应的影响

研究了不同偏置条件对PMOS探头样品辐照响应的影响.在－1～1MV/cm的电场范围内,获得了偏置对PMOS剂量计辐照响应灵敏度和线性度的影响规律.利用“空穴陷阱薄层(Hole Traps Sheet)”模型,结合辐射感生界面电荷的栅偏置电场相关性,分析了实验结果.     

偏置对PMOS剂量计辐照响应的影响

研究了不同偏置条件对ＰＭＯＳ探头样品辐照响应的影响．在－１～１ＭＶ／ｃｍ的电场范围内,获得了偏置对ＰＭＯＳ剂量计辐照响应灵敏度和线性度的影响规律．利用“空穴陷阱薄层（ＨｏｌｅＴｒａｐｓＳｈｅｅｔ）”模型,结合辐射感生界面电荷的栅偏置电场相关性,分析了实验结果．     

新型功函数测量系统的建立及其应用研究

采用接触势差法,设计并组建了功函数测量系统.该系统由信号发生单元、振动单元和检测单元组成,信号发生单元输出低频正弦信号使参比电极振动,调节振动单元偏压使检测单元输出信号为零,通过计算加载偏压和标准参比电极的偏差可得样品功函数值.用该系统测量了UV处理对ITO功函数的影响,发现ITO功函数的提高存在极限值并可改善有机电致发光器件(OLED)的性能.该系统可在空气中快速、准确测量表面功函数.     

用Fowler-Nordheim公式测定ITO功函数的研究

通过制备双边注入型单载流子器件ITO/TPD(NPB)/Cu,运用Fowler-Nordheim(F-N)公式变换,消除了载流子有效质量和器件厚度因素的影响,提高了测量的精度,简单准确地测定了ITO的功函数.实验测得值分别为4.85 eV、4.88 eV,与ITO的文献报道值接近.该方法操作简便,可以用来测定半导体和金属电极特别是合金电极的功函数.     

Modulation of the effective work function of TiN metal gate for PMOS application

It is important to find a way to modulate the work function of TiN metal gate towards the valence band edge of Si,which can meet the lower threshold voltage requirement of p-type metal-oxide-semiconductor（MOS） transistor.In this work,effects of TiN thickness,post-deposition annealing（PDA）,oxygen incorporation and N concentration variation on the work function of TiN metal gate in MOS structures are systematically investigated. It can be found that the work function positively shifts at the initial stage as the thickness of the TiN layer increases and stabilizes at such a thickness.PDA at N₂ ambience with a trace of O₂ can also cause a positive shift in the work function of TiN metal gate.The same tendency can be observed when oxygen is incorporated into TiN.Finally, increasing the N concentration in TiN can also positively shift the work function.All these measures are effective in modulating the TiN metal gate so that it is more suitable for PMOS application.     

Oxygen incorporation in TiN for metal gate work function tuning with a replacement gate integration approach

In this study, we used oxygen to increase the work function of a TiN gated stack. To prevent the EOT growth associated with oxygen incorporation, we proposed a novel replacement gate flow, where oxygen incorporation by O₂ anneal on a thin TiN layer was performed after dopant activation. With this novel flow, a maximum work function tuning range of ∼0.32 eV was achieved without significant EOT penalty, making it attractive for p-type metal gate integration.     

Annealing effect on the metal gate effective work function modulation for the Al/TiN/SiO2/p-Si structure

In this work, the thermal annealing effect on the metal gate effective work function (EWF) modulation for the Al/TiN/SiO₂/p-Si(1 0 0) structure was investigated. Compared with the sample of TiN/SiO₂/p-Si(1 0 0) structure, for the sample additionally capped with Al the flat band voltage has a very obvious shift as large as 0.54 V to the negative direction after forming gas annealing. It is also revealed that the thermal budget can effectively influence both the EWF of the gate electrode and the thickness of the gate dielectric layer when a post annealing at 600 °C with different soak times was applied to the samples with Al cap. Material characterization indicates that the diffusion of Al and the formation of Al oxide during annealing should be responsible for all the phenomena. The interface trap density Dit calculated from the high-frequency C-V and the laser-assisted high-frequency C-V curves show that the introduction of Al does not cause reliability problem in the Al/TiN/SiO₂/p-Si structure.     

反应溅射的TaN金属栅的材料性质和有效功函数研究

本文研究了反应溅射的TaN金属栅的电阻,晶体结构和有效功函数(EWF). 原始生长的TaN薄膜具有fcc 结构。经过900 oC后金属退火（PMA）,反应溅射时的氮气流量大于6.5 sccm的TaN仍保持fcc 结构,而反应溅射时的氮气流量小于6.25 sccm的TaN显示了微结构的变化。接着测量了用TaN作为电极的SiO2 和HfO2 栅平带电压随TaN反应溅射时氮气流量的变化。结果显示在介电质和TaN的界面会形成一个电偶矩,它对EWF的贡献会随TaN中的Ta/N比、介质层的性质和 PMA条件不同而变化。     

Material properties and effective work function of reactive sputtered TaN gate electrodes

The resistivity,crystalline structure and effective work function（EWF） of reactive sputtered TaN has been investigated.As-deposited TaN films have an fcc structure.After post-metal annealing（PMA） at 900℃,the TaN films deposited with a N₂ flow rate greater than 6.5 sccm keep their fee structure,while the films deposited with a N₂ flow rate lower than 6.25 seem exhibit a microstructure change.The flatband voltages of gate stacks with TaN films as gate electrodes on SiO₂ and HfO₂ are also measured.It is concluded that a dipole is formed at the dielectric-TaN interface and its contribution to the EWF of TaN changes with the Ta/N ratio in TaN,the underneath dielectric layer and the PMA conditions.     

Top-TiN生长条件及TaN厚度对MOSCAP栅叠层有效功函数的影响

我们引入TaN/TiAl/top-TiN三层结构,通过变化TaN的厚度及top-TiN的生长条件来调节TiN-based金属栅叠层的有效功函数。实验结果显示：较薄的TaN和PVD-process生长的top-TiN组合可以得到较小的有效功函数(EWF),而较厚的TaN和ALD-process生长的top-TiN组合可以得到较大的有效功函数(EWF),文中EWF有从4.25eV to 4.56eV的变化。同时文中也给出了TaN厚度及top-TiN的生长条件调节有效功函数(EWF)的物理解释。与PVD-process在室温条件下生长TiN相比,ALD-process TiN是在400 ℃条件下生长的,400 ℃ ALD-process TiN 可以为整个工艺过程提供更多的热预算,从而促进更多的Al原子扩散进入top-TiN,导致扩散进入到bottom-TiN的Al原子数量减少。另外,厚的TaN也会阻止Al原子进入bottom-TiN。这些因素都减少了bottom-TiN中Al原子的数量,减弱了Al原子对有效功函数的调节作用,从而引起EWF的增加。     

Tuning effective metal gate work function by a novel gate dielectric HfLaO for nMOSFETs

Using a novel HfLaO gate dielectric for nMOSFETs with different La composition, we report for the first time that TaN (or HfN) effective metal gate work function can be tuned from Si mid-gap to the conduction band to fit the requirement of nMOSFETs. This is explained by the change of interface states and Fermi pinning level by adding La into HfO/sub 2/. The superior performances of the nMOSFETs compared with those using pure HfO/sub 2/ gate dielectric are also reported, in terms of higher crystallization temperature and higher drive current I/sub d/ without sacrifice of very low gate leakage current, i.e. 5-6 orders reduction compared with SiO/sub 2/ at the same equivalent oxide thickness of /spl sim/1.2-1.8 nm.     

Modulation of the effective work function of fully-silicided (FUSI) gate stacks

A systematic analysis of the different methods of work function (WF) tuning for gate stacks using fully silicided (FUSI) gate electrodes is presented. We show that FUSI gates have the potential to meet the WF requirements for future nodes, including high performance applications, achieving band edge WF, with total WF range of up to ∼900 meV. The introduction of dopants (such as Sb, As, P, B) by ion implantation is shown to be effective to tune the WF of NiSi or Ni₃Si₂ on SiO₂ or SiON by ∼550 meV, but is ineffective on HfSiON or for Ni-richer silicides. Different silicide phases can be used for Ni FUSI gates on HfSiON dielectrics, taking advantage of the higher WF of metal-rich silicides, achieving a WF range of ∼400 meV. This method is not effective, however, on SiON dielectrics. The introduction of Lanthanides by several techniques (such as dielectric cap deposition, ion implantation into poly-Si, or at metal deposition) that result in the modification of the dielectric, is found, for Ni FUSI gates, to achieve low WF (∼4.0 eV) suitable for NMOS. Similarly, incorporation of Al can be used to achieve PMOS type WF, as well as the use of metal-rich Ni and/or Pt based FUSI gates (with WF as high as 5.0 eV).